Alphaviruses (Togaviridae family) cause considerable human and animal morbidity and mortality. There are currently no specific treatments for diseases caused by these viruses. The zinc-finger antiviral protein (ZAP) is a host protein that when over expressed mediates potent inhibition of alphaviruses, including the prototype Sindbis virus, as well as viruses in the Retroviridae and Filoviridae families. Recently, small RNAs similar to micro or small interfering RNAs, but directed to gene promoter sequences (anti-gene, or agRNAs), have been found to mediate transcriptional up- and down regulation. The objectives of this project are to up regulate expression of endogenous ZAP and test whether this ameliorates symptoms due to alphavirus infection in an in vivo model. The objectives will be accomplished in two specific aims. In Aim 1, agRNAs directed to ZAP promoter sequences will be tested in cell culture for ZAP transcriptional up regulation activity. Active sequences will be characterized for efficacy and specificity of the ZAP mRNA and protein up regulation and their effect on Sindbis virus replication. In Aim 2, the active agRNAs will tested in a well characterize murine model for their ability to up regulate ZAP expression and reduce disease caused by neurovirulent Sindbis virus infection. If successful, the work will be of high impact, adding knowledge to this recently discovered transcriptional control pathway, and opening up a whole new approach to the treatment of alphavirus infection. The work will be more broadly applicable to the treatment of infection by members of the Retrovirus and Filovirus families. Moreover, the conceptual approach could be applied to treat any infectious disease, as well as any disease or condition that would benefit by up regulation of a specific gene or set of genes.